The present invention relates to disc brakes for vehicles. In particular, this invention is a structure which improves the high stress levels in the hat section and the friction ring as well as coning of the friction ring causing a reduced service life of the disc brake.
Conventional brake disc designs have shown numerous disadvantages. The main function of the brake disc is to absorb the kinematic energy. The kinematic energy turns into heat that the brake disc must absorb. This thermal load on the brake disc is in most cases more severe than the mechanical loads. During a brake application with a conventional brake disc the friction ring expands radially and causes the hat section in the disc to expand with the friction ring. This introduces bending stress in the hat section. Material is added in the hat section to withstand the bending stress, thus stiffening the hat section. The stiff hat section increases the stress in the friction ring and causes it to tend to take on the shape of a cone. The coning decreases the service-of-life of the brake disc as well as the brake pad.
The present invention relates to improvements in disc brakes in the areas just described. In this invention a front or rear brake disc consists of a hat section and a friction ring secured to the hat section. The hat section is cast together with the friction ring by a number of circumferential spaced radial ribs around the hat section. The ribs connect the hat section so that the ribs can move relative to the ring as a result of the mass of the friction ring.
A part of the rib that is cast into the friction ring has a constant cross-section. The ribs are cast into the friction ring without creating a melting zone between the hat section and the friction ring. Stated otherwise, the ribs do not bond to the friction ring. The ribs transfer the brake torque between the friction ring and the hat section. The constant cross-section of the rib allows the friction ring to expand freely in the radial direction but constrains axial and circumferential displacement between the friction ring and the hat section. The minimum length of the rib is the length that is sufficient to absorb the accumulated radial displacement between the friction ring and the hat section. The tip of the rib has a curved shape to minimize the stress introduced when a rotation occurs in the circumferential direction between the friction ring and the hat section.
Other general and more specific aspects of this invention will be set forth in the ensuing description and claims.